Adiantum aleuticum (CC BY 2.0) Miguel Vieira/flickr.com, cropped

Scientific Name: Filicopsida

Status: Extant (alive today)

Oldest fossil anywhere: Devonian of Australia (about 400 million year old)

Oklahoma fossil record: Macrofossils have been found in Oklahoma rocks deposited during the Pennsylvanian and Permian Periods.

Ferns are generally small plants growing in damp environments, but may grow as trees (without any wood) that reach up to about 30 feet (10 meters) tall.

Ferns do not have seeds; they have leaves and roots, vascular tissue and use spores to reproduce.

Recently, genetic studies have demonstrated that Horsetails, once considered a distinct group, are actually closely related to one group of ferns. Ferns and horsetails are grouped together in Monilophyta.